Internal bleeding rarely occurs after thyroid luminal surgery. Internal bleeding after thyroid luminal surgery may be due to dislodged thyroid ligatures, poorly tied knots, and bleeding from the blood vessels of the recurrent laryngeal nerve. Patients with internal bleeding after surgery should inform the doctor promptly for relevant treatment. 1. Dislodging of thyroid ligature: Because of the high arterial pressure, when the upper and lower extremity thyroid vessels and the middle vein ligature are dislodged, it is easy to bleed internally. 2. Insecure knotting: During the operation, internal bleeding will occur when the thread is loosened and causes bleeding and oozing on the residual surface of the gland due to insecure knotting or poor suturing. 3. Bleeding from the blood vessels of the recurrent laryngeal nerve: Since the blood vessels around the recurrent laryngeal nerve are relatively dense, the blood vessels are inadvertently damaged during the operation. When the patient exerts force or the pressure of blood vessels increases after the operation, internal bleeding will occur. Therefore, the surgeon needs to be careful during surgery and operate strictly to reduce the incidence of bleeding. Postoperative patients who have a swollen area with pressure and fluid wave sensation in the operated area and may have internal bleeding should inform the doctor in time for relevant treatment.